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.TH T_SNDUDATA 3NSL "May 7, 1998"
.SH NAME
t_sndudata \- send a data unit
.SH SYNOPSIS
.LP
.nf
#include <xti.h>




\fBint\fR \fBt_sndudata\fR(\fBint\fR \fIfd\fR, \fBconst struct t_unitdata *\fR\fIunitdata\fR);
.fi

.SH DESCRIPTION
.LP
This routine is part of the \fBXTI\fR interfaces which evolved from the
\fBTLI\fR interfaces. \fBXTI\fR represents the future evolution of these
interfaces. However, \fBTLI\fR interfaces are supported for compatibility. When
using a \fBTLI\fR routine that has the same name as an \fBXTI\fR routine, the
\fBtiuser.h\fR header file must be used.  Refer to the  \fBTLI\fR
\fBCOMPATIBILITY\fR section for a description of differences between the two
interfaces.
.sp
.LP
This function is used in connectionless-mode to send a data unit to another
transport user. The argument \fIfd\fR identifies the local transport endpoint
through which data will be sent, and \fIunitdata\fR points to a
\fBt_unitdata\fR structure containing the following members:
.sp
.in +2
.nf
struct netbuf addr;
struct netbuf opt;
struct netbuf udata;
.fi
.in -2

.sp
.LP
In \fIunitdata\fR, \fIaddr\fR specifies the protocol address of the destination
user, \fIopt\fR identifies options that the user wants associated with this
request, and \fIudata\fR specifies the user data to be sent. The user may
choose not to specify what protocol options are associated with the transfer by
setting the \fIlen\fR field of \fIopt\fR to zero. In this case, the provider
uses the option values currently set for the communications endpoint.
.sp
.LP
If the \fIlen\fR field of \fIudata\fR is zero, and sending of zero octets is
not supported by the underlying transport service, the \fBt_sndudata()\fR will
return  -1 with \fBt_errno\fR set to \fBTBADDATA\fR.
.sp
.LP
By default, \fBt_sndudata()\fR operates in synchronous mode and may wait if
flow control restrictions prevent the data from being accepted by the local
transport provider at the time the call is made.  However, if  \fBO_NONBLOCK\fR
\fBis\fR \fBset\fR \fBby\fR \fBmeans\fR \fBof\fR \fBt_open\fR(3NSL) or
\fBfcntl\fR(2), \fBt_sndudata()\fR will execute in asynchronous mode and will
fail under such conditions. The process can arrange to be notified of the
clearance of a flow control restriction by means of either \fBt_look\fR(3NSL)
or the EM interface.
.sp
.LP
If the amount of data specified in \fIudata\fR exceeds the TSDU size as
returned in the \fItsdu\fR field of the \fIinfo\fR argument of
\fBt_open\fR(3NSL) or \fBt_getinfo\fR(3NSL), a \fBTBADDATA\fR error will be
generated. If \fBt_sndudata()\fR is called before the destination user has
activated its transport endpoint (see \fBt_bind\fR(3NSL)), the data unit may be
discarded.
.sp
.LP
If it is not possible for the transport provider to immediately detect the
conditions that cause the errors \fBTBADADDR\fR and \fBTBADOPT\fR, these
errors will alternatively be returned by \fIt_rcvuderr.\fR Therefore, an
application must be prepared to receive these errors in both of these ways.
.sp
.LP
If the call is interrupted, \fBt_sndudata()\fR will return \fBEINTR\fR and the
datagram will not be sent.
.SH RETURN VALUES
.LP
Upon successful completion, a value of  \fB0\fR is returned.  Otherwise, a
value of  -1 is returned and \fBt_errno\fR is set to indicate an error.
.SH VALID STATES
.LP
\fBT_IDLE\fR.
.SH ERRORS
.LP
On failure, \fBt_errno\fR is set to one of the following:
.sp
.ne 2
.na
\fB\fBTBADADDR\fR\fR
.ad
.RS 15n
The specified protocol address was in an incorrect format or contained illegal
information.
.RE

.sp
.ne 2
.na
\fB\fBTBADDATA\fR\fR
.ad
.RS 15n
Illegal amount of data. A single send was attempted specifying a TSDU greater
than that specified in the \fIinfo\fR argument, or a send of a zero byte TSDU
is not supported by the provider.
.RE

.sp
.ne 2
.na
\fB\fBTBADF\fR\fR
.ad
.RS 15n
The specified file descriptor does not refer to a transport endpoint.
.RE

.sp
.ne 2
.na
\fB\fBTBADOPT\fR\fR
.ad
.RS 15n
The specified options were in an incorrect format or contained illegal
information.
.RE

.sp
.ne 2
.na
\fB\fBTFLOW\fR\fR
.ad
.RS 15n
\fBO_NONBLOCK\fR was set, but the flow control mechanism prevented the
transport provider from accepting any data at this time.
.RE

.sp
.ne 2
.na
\fB\fBTLOOK\fR\fR
.ad
.RS 15n
An asynchronous event has occurred on this transport endpoint.
.RE

.sp
.ne 2
.na
\fB\fBTNOTSUPPORT\fR\fR
.ad
.RS 15n
This function is not supported by the underlying transport provider.
.RE

.sp
.ne 2
.na
\fB\fBTOUTSTATE\fR\fR
.ad
.RS 15n
The communications endpoint referenced by  \fIfd\fR is not in one of the states
in which a call to this function is valid.
.RE

.sp
.ne 2
.na
\fB\fBTPROTO\fR\fR
.ad
.RS 15n
This error indicates that a communication problem has been detected between XTI
and the transport provider for which there is no other suitable XTI error
\fB(t_errno)\fR.
.RE

.sp
.ne 2
.na
\fB\fBTSYSERR\fR\fR
.ad
.RS 15n
A system error has occurred during execution of this function.
.RE

.SH TLI COMPATIBILITY
.LP
The \fBXTI\fR and \fBTLI\fR interface definitions have common names but use
different header files. This, and other semantic differences between the two
interfaces are described in the subsections below.
.SS "Interface Header"
.LP
The \fBXTI\fR interfaces use the header file, \fBxti.h.\fR \fBTLI\fR interfaces
should \fInot\fR use this header.  They should use the header:
.br
.in +2
#include <tiuser.h>
.in -2
.SS "Error Description Values"
.LP
The \fBt_errno\fR values that can be set by the \fBXTI\fR interface and cannot
be set by the \fBTLI\fR interface are:
.br
.in +2
\fBTPROTO\fR
.in -2
.br
.in +2
\fBTBADADDR\fR
.in -2
.br
.in +2
\fBTBADOPT\fR
.in -2
.br
.in +2
\fBTLOOK\fR
.in -2
.br
.in +2
\fBTOUTSTATE\fR
.in -2
.SS "Notes"
.LP
Whenever this function fails with \fBt_error\fR set to \fBTFLOW,\fR
\fBO_NONBLOCK\fR must have been set.
.SS "Option Buffers"
.LP
The format of the options in an \fBopt\fR buffer is dictated by the transport
provider. Unlike the \fBXTI\fR interface, the \fBTLI\fR interface does not fix
the buffer format.
.SH ATTRIBUTES
.LP
See \fBattributes\fR(7)  for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
MT Level	Safe
.TE

.SH SEE ALSO
.LP
.BR fcntl (2),
.BR t_alloc (3NSL),
.BR t_bind (3NSL),
.BR t_error (3NSL),
.BR t_getinfo (3NSL),
.BR t_look (3NSL),
.BR t_open (3NSL),
.BR t_rcvudata (3NSL),
.BR t_rcvuderr (3NSL),
.BR attributes (7)
